Pressure operated switch



o mw 0 NE N mmm MR OAL/ m TGA O @50% M 7 VNN O "n 2 WAM .uw it. B CD f5 N 7, UE 6 D 3 Y s, w B 2 m m w L H O A C 2 6I E m M. M l 8 S D G R D l l. E 4 m m M l e 4 F m E V w BOL m9 if. m m m 2 m If L O l d l G my E IX. 3 .vfat 6 B m n 4| 4m v o o R 2 6 5 7 l l D P 2 5 PWA: l 8 O M 6 6 1m 2 l mw O l 2 6 l 6 H2 www# l- 8 y T ,w 7 0 @IIIM .M l 2 mwsmv m B ,9 M I. 4 1. y G 2 PH J Patented Jan. 2, 1951 UNITED STATES vPMI"ENT OFF-ICE Viale, Birmingham, Mich., assignors fto Vickers Incorporated, Detroit, Mich., a corporation of Michigan ApplicationNoveniber 14, 19317, Serial lNo. 78`5,902

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The :present invention relates -to power transmissions of the Vhydraulic type, particulariy `to e pressure `switch for use in power ytrapsmissiehs of this character. Power ytransmissions of this type are generallfycoinprised of a pressure huid-source connected to one'or more 'fluid motors `for-driving the sa'me and directional control valves for rcone troll-ing :the -iiow of fluid to `the motors. The directional #con-trol valves are frequently operated electrically as lby solenoids. Where the transmisM sion installation requires that the solenoids 'ne operated in response to pressure changes inthe system, pressure 'switches are employed.

The number of different possible hydraulic oircuits in which a :pressure switch may oe used is almost countless, 'each circuit requiring slighthI different pressure responses oi the `pressure switch for staisfactory operation. In addition, the circuits Vary as to diiierential between cutn in and. cut-'out pressure.

in the past, it was Ynecessary to use different types of pressure switches to .meet various pres'n sure operating requirements. Although some witches were 1of the adjustable type, the -cutin and cut-out pressure response points could not be individually selected.

ylit -is an object of this invention to provide a pressure switch system in which both the cut-in and cut-out points may be Vindependently se lected, and which may be adjusted to provide any d-iiierential desired.

t is a furtherobject of this invention to provide an improved pressure responsive switch which is adapted for installation in circuits hav'- ing widely different pressure characteristics.

It is also an object of this invention to prov-ide a lpressure'switch of this character of simpe and reliable construction which is inexpensive to manufacture and which is readily adaptable to various installta-ion requirements by a simple =adjustin-ent.

Further objects and advantages of the present invention will be apparent from thefoliowing de'- sc-ription, reference being had yto the 'accompanying drawing wherein a preferred form of the present invention is clearly shown.

In the drawing:

Figure l is a sectional view of a preferred torre of the present 4invention taken on line l-e-i of rFigure 2.

Figure 2 is a 'sectional View taken on line 2- 2 ofrFzigfure 1.

Figure 3 isa diagrammatic view embodying a preferred form ofthe present invention.

.Refer-ring vnow tti-Figure 1:, there is vvsho-wp a f 2 pressure switch t5 'comprised of a U-'shaped housing :l2 provided with va pressure supply `port i4 land fra drain port i6.

rThe pressure supply port 'I4 is connected by `a passage I3 toa pair of vertical bores 2Q `and 22 within which pistons 24 and :25 are respa'ztivelsfP mounted- TheboresZfil and 22 are close-:l at their lower ends hy plugs 28 and 35.

Referring now to Figures land 2, the pistons `and 25 are limited in `their vertical 'movement oy duplicate pins 32 which are sta-tionarily mounted 'by means oi `mounting screws 34 vin du plicate bores 3E which respectively intersect the bores 2S 'and 22. The pistons 24 and 25 are pro vided with transverse bores 33 and 43, respective* Iy, through which the pins 32 are inserted. The diameters 'of the ypins 32 and of the transverse hores 33 Aand 45 maybe carefully 'selected 'to 'dee termine ithe total reciprocal movement oi the pistons lt and 2B. The ,pistons 24 and 255 are biased to the position 'shown by means of springs Vt2 and 44 oi .predetermined resistance which are :iwunted in upper and lower spring retainers d6 and 48. The :lower spring retainers 't8 abut 'duplicate piston retainers 55, the function 'of which is to operate a pair of plunger pins '52 and 54 mounted lin vertical bores 56 and 53 which are located on diierent planes. The resistance of the springs 42 and 44 .may be independently adjusted by means of adjusting lscrews and 62 for yselective-ly varying the Vcut-in and cut-out pressures of the switching system..

At the bottom of the housing l2, a .pair of switches 54 and Gt are `connected to a bracket S3 vby means 'of through bolts 70. The bracket tt :is fastened to the l*bottom Aof the housing i 2 by means of mounting screws T2. The switches may .preferably be voi the ysingle-pole single throw Did Preferably two duplicate switches 'of the normally closed type are used in the invention which are maintained in the open position as follows: The switches 54 and 5% are provided with plungers i4 and 'l which are biased downwardly yby the plunger pins 52 and 54 so as vto normally maintain the switches lin the open po-d sition shown. Thus, when the pistons 24 and 2S Aare actuated upwardly, the plungers snap upwardly to close the switches.

The body I2 and the switches are protectively closed by Acover i3. It should be noted that all of .the pressure actuated mechanism is mounted `in one side of the U-shaped body and that the pressure fluid supply to the pistons is 'delivered through a single kconduit i8 which intersects nger type which are well known in the prior vmanner to an electrical supply source.

both bores 20 and 22 within which the pistons 24 and 26 are mounted. The cavity formed between the two sides of the U-shaped housing provides a convenient mounting location for the springs 42 and 44. The arrangement is such that the switches may be conveniently fastened to the same side of the housing in which the pressure actuating mechanism-is mounted. The U-shaped housing not only provides a cavity for convenient mounting of the springs 42 and 44 but also permits the springs to perform the dual function of biasing both the iiuid operated pistons and the plunger pins which actuate the switches to one of their positions of operation. The opposite side of the housing provides abutment means for the springs so that the two springs are only opposed by the pressure biased pistons, thus obviating linkage which would tend to introduce friction. The opposite side of the housing not only provides an abutment for the springs but provides mounting structure for the adjusting screws 60 and 62 which are placed closely together to facilitate adjustments of the switching mechanism.

, Referring now to Figure 3, for the purpose of illustrating the operation of the switching system, there is shown a solenoid operated control valve indicated. by the numeral 80.` The control valve 80 is adapted to be operated by yright and left end Solenoids indicated respectively by the numerals 82 andV 84. One terminal of the solenoid 82 is adapted to be connected to -a line 86 by lines 98 and 90. The other terminal of the solenoid 82 is adapted to be connected by a line 92 to the rst of a pair of contacts 94 and -96 of a holdingrelay 98 which is also provided with two other pairs of contacts and |02 and |04 and |06. The line 86 is connected to one end of the relay 98. The coil of the relay 98, indicated by the numeral |08, operates a plunger core 0 with which is associated an varm ||2 for controlling the contacts 94 and 96, an arm ||4 for controlling the contacts |00 and |02, and an arm ||6 for controlling the contacts |04 and |06. The relay 98 when de-energized is4 in the position shown and when energized, closes the contacts |04 and |06 and |00 and |02,

vand breaks the contacts 94 and 96.

One terminal of the solenoid 84 is also connected to the line 89 while the other terminal thereof is connected by a line ||8 to the contact |00 of the relay 98.

Referring now to the switches 64 and 66, the

yengage the plungers 16 and 14 of the switches 64 and 66.

' In the position shown, the lever arm |20 breaks the connection between a line |24 and a line |26 while the lever arm |22 breaks the connection between a line |28 and a line |30. Both of the lines |24 and |28 are connected to a line .|32 which is connected at one extreme end to the contact |02 of the relay 98. The opposite end of the line |32 together with that of line 86 is adapted to be connected in the well known The lines |26 and |30, which are respectively connected to the switches 64 vand 66 are connected -a't their opposite ends to the contacts 04 and |06 off the relay 98. A line |34 connects the Lline2l32 to the other end ofthe relay-98 for the purpose of energizing the same and a line |36 connects the line |32 to the contact 96 of the relay 98.

Referring now to Figures 1, 2, and 3, in operation, and presuming for the purpose of illustration that switch 64 will be operated at 500 lbs. per square inch and that switch 66 will be operated at 1000 lbs. per square inch, with the pressure of the system below 500 lbs. per square inch, solenoid 82 of the control valve 80 is energized, and solenoid 84 and relay 98 are deenergized. Solenoid 82 is energized by means of a circuit being formed by lines 86, 88, and 90, the terminals of the solenoid 82, line 92, contacts 94 and 96 of relay 98, and the lines |36 and |32. When the pressure reaches 500 lbs. per square inch, the plunger 26 is lifted, and the bias force retaining plunger pin 54 on the plunger 79 of switch 64 is removed so as to operate lever arm to the closed position. The operation of switch 64 to the closed position does not change the circuit which energizes solenoid 82 and de-energizes the solenoid 84 and relay 98.

' The operation of the switch 64 merely readies the system for a holding circuit to be later established and hereinafter described. When the pressure reaches 1000 lbs. per square inch, the piston 24 is lifted against the resistance of spring 42. With the bias force on plunger pin 52 removed, plunger `|4 of the switch 66 operates the lever arm |22 of the switch 66 also to the closed position so as to connect line |28 to line |30. A circuit is immediately established for energizing the relay 99 by the lines |32 and |28, switch 66, lines |30 and |34, coil |08 and line 86. When the relay 98 is energized, the arms H2, ||4, and ||6 are lifted so as to break the contacts 94 and 96 and to close the contacts |02 and |00 and |04 and |06. With contacts 94 and 96 broken, the circuit energizing solenoid 82 is broken and the solenoid becomes de-energized. The solenoid 84 is energized by the closure of contacts |00 and |02, the following circuit being established: Lines 86 and 88, the terminals of the solenoid 84, line IIS, contacts |00 and |02 of the relay 98, and line |32. Simultaneously, with the opening of the other relay contacts, closure of contacts |04 and 06 completes the relay holding circuit which holds the relay energized through the following path; one end of the relay coil |08 is connected to line 86 and the other end of the relay coil is now connected to line |32 through lines |34 and |30, operated contacts |96 and |04, line |26, switch 64, and line |24. When the pressure falls below 1000 lbs. per square inch, the lever arm |22 of the switch 66 is operated by means of the spring 42 forcing the retainers 48 and 50 to shift the plunger pin 52 downwardly so as to operate the plunger 14. With the switch 66 in the open position, the relay is maintained in the energized position by means of the holding circuit previously established. Solenoid 84 continues to be energized and solenoid 82 continues to be de-energized. When the pressure falls below 500 lbs. per square inch, the spring 44 forces the retainers 48 and 50 downwardly against the plunger pin 54 which j shifts the plunger 76 of the switch 64 to operate ,energized while solenoid 82 becomes energized.

The cut-in and cut-out pressures of the switching unit |0 may be easilyselectively determined by adjustment of the screws 60 and 62. Thus, both the cut-in and cut-out pressures may be raised or lowered, and in addition, either the cut-in or cut-out pressure may be raised or lowered, independently of the other.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claim which follows.

What is claimed is as follows:

A pressure responsive Switching mechanism comprising a substantially U-shaped housing having two sides with a cavity formed therebetween, a pair of hydraulically operated pistons shiftably mounted in the first side of the housing, separate resilient means mounted in the cavity and biasing each piston to one position of operation, means forming a single, common fluid pressure supply conduit in the rst side of the housing and connected to the pistons, said pistons being responsive to predetermined increases of pressure for shifting to a second position and overcoming the resilient biasing means, a pair of switches fastened to the first side of the housing, said switches being of the open and close type and biased to one position of REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Taylor Oct. 4, 1932 Dezotell Mar. 10, 1936 Shivers Aug. 22, 1939 Pike Dec. 19, 1939 Hammond Feb. 24, 1942 Ol Nov. 10, 1942 Jan. 12, 1943 Number 

